Patent GB-669744-A (GB)
Title: Improvements in or relating to pattern-controlled machine tools
IPC: B23Q35/18
Filed: 1948-12-09
Abstract: 669,744. Copy-milling. CINCANNATI MILLING MACHINE CO. Dec. 9, 1948 [Dec. 10, 1947], No. 31864/48. Class 83 (iii). A pattern-controlled machine tool, such as a die-sinking machine, comprises hydraulicallyoperated means for shifting a pattern and work in relation to a tracer finger and cutting tool, a control valve mounted in the housing of the tracer finger for governing the rate and direction of resultant movement produced by the hydraulically-operated means in accordance with deflections of the tracer finger by the pattern, and a power device activated by deflections of the tracer finger to adjust the housing of the tracer finger so as to impart a lead to the latter relatively to the cutting tool in said direction of resultant movement. The tracer housing 23, Fig. 10, is mounted by an eccentric device 271 in a frame 32 which also supports the housing by means of a bifurcated link 34 and crank 37 whereby on rotation of the eccentric, the housing is free to swing about the pivot pin 36, Fig. 15, and impart a crankpath motion to the point of the tracer 24. The eccentric device, which is disposed in an antifriction bearing 26 in the housing 23, comprises an outer sleeve 27 held against axial movement, and an inner sleeve 28 axially slidable on a shaft 29 mounted in the frame 32; the sleeve 28 is slidable in an inclined bore in the sleeve 27 in order to adjust the eccentricity of the device. The tracer 24 is supported by a diaphragm 69 clamped peripherally to the housing 23 and at its inner end acts through a ball 76 on a second diaphragm 78 which deflects with deflection of the tracer and thereby causes axial movement of a connecting rod 82 interposed between the diaphragm 78 and a valveplunger 83 in the tracer housing. The pattern and work on the one hand, and the tracer and cutter on the other hand, are movable relatively in a direction axially of the cutter and also at right-angles to this direction by power-operated slides under the control of hydraulic motors 55, 52, Fig. 18. For this purpose, the work and pattern may be actuated by one slide and the cutter and tracer by the other, or both the desired relative movements may be given either to the pattern and work or tracer and cutter. The flow of pressure fluid from a pump 58 to the motors 52, 55 is governed by valves 60, 59, the plungers 65, 64 of which are controlled by a second eccentric device 66 constructed similarly to the device 27<1> and rotated therewith, but in the opposite direction. The device 66 is mounted on a shaft 107, Fig. 3, which is driven by a gear 103 thereon meshing with a rack piston 102, Fig. 18, in the cylinder 100 of a hydraulic motor; the shaft 107 drives the eccentric 27<1> through a gear 43, Fig. 10, on the shaft 29. Adjustment of the throws of the two eccentrics 27<1>, 66 is effected by axially sliding the inner sleeves 28, 114 thereof, this operation being performed simultaneously for both eccentrics by means of a lever 121, Fig. 3, acting upon a spool 132 which is splined on a shaft 134. On rotation of the shaft 134, the spool 132, which is urged to the left by a spring 135, takes up different axial positions as determined by the position of engagement of a setscrew 136 on an arm 133 with an adjustablymounted stop-plate 137. Rotation of the shaft is effected by a cam 154 acted upon by a knob 160 and engaging a pin 152 on the cranked end of the shaft. The relative disposition of the two eccentrics is so arranged that the tracer point is always moved by the eccentric 271 in the same direction as the slides are moved by the eccentric 66 and is therefore caused to lead the cutter in the direction of movement as determined by the valves 59, 60. The hydraulic motors 52, 55, 100 and the pump 58 are arranged in a hydraulic circuit with the tracer valve as shown in Fig. 18. With the tracer out of engagement with the pattern, the tracer plunger 83 is urged to the left by a spring 84 so that pressure fluid passes through ports 86, 88 to a reversing valve 92 and thence through a line 98 to the upper end of the cylinder 100; the gear 103 is thereby rotated. by the rack piston 102 so as to dispose the two eccentrics in their correct starting positions. By operating the lever 199 of a control valve 161, pressure fluid from the pump passes to one end of the motor 55 so as to move the pattern into engagement with the tracer and thereby cause the tracer valve plunger 83 to move to its central position. The operator then sets the control knob 160 to give the eccentrics the desired feed rate and opens a main control valve 186 so that the motors 52, 55 are then under the control of the valves 59, 60 as actuated by the eccentric 66. Initially, with the eccentrics in the position shown in Fig. 15, the valve 60 is operated to cause the pattern to continue its movement towards the tracer, thereby moving the tracer plunger 83 to the right; such movement slows down or stops the motor 55 and permits pressure fluid to pass across the tracer valve to the reversing valve 92 and thence to the lower end of the cylinder 100, causing reverse rotation of the gear 103 and eccentrics. Thereafter, deflection of the tracer finger by the pattern controls the valve plunger 83 and, through it, rotation of the gear 103 and eccentrics 27<1>, 66; the movement of the slides then continues under the control of the eccentric 66, and the tracer is always provided with the desired lead over the cutter by the eccentric 271. After each stroke across the machine, the position of the reversing valve 92 is automatically reversed by the action of dogs on the machine engaging a trip lever 221 so as to reverse the position of the plunger 216 of a pilot valve 213, and thereby change the direction of flow of pressure supply to the valve 92.